Expandable intervertebral implants

ABSTRACT

Interbody spacers are expandable horizontally and vertically by an application of axial force, and lockable in an expanded configuration. The spacers include support members interconnected to end bodies by pivotable link members. The spacers are introduced between vertebral bodies in a compressed configuration and expanded to fill the intervertebral space and provide support and selective lordotic correction. Graft material may be introduced into the expanded spacer. Provisional and/or supplementary locking means lock the spacers in the expanded configuration. Embodiments of the spacers include symmetrically and asymmetrically configured spacers. Methods of expansion include symmetric expansion or asymmetric expansion along each of two directions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/244,446 filed Aug. 23, 2016, entitled“Expandable Intervertebral Implants”, which claims the benefit of U.S.Provisional Application No. 62/209,604, filed Aug. 25, 2015, entitled“Expandable Intervertebral Implant”, which are herein incorporated byreference in their entirety.

FIELD OF THE INVENTION

This invention generally relates to the field of spinal surgery, andmore particularly, to spinal cages used in fusing adjacent vertebrae.

BACKGROUND OF THE INVENTION

In a vertebrate spine, the spinal disc and/or vertebral bodies may bedisplaced or damaged due to trauma, disease, degenerative defects, orwear over an extended period of time. One result of this displacement ordamage to a spinal disc or vertebral body may be chronic back pain. Acommon procedure for treating damage or disease of the spinal disc orvertebral body may involve partial or complete removal of anintervertebral disc. An implant, which may be referred to as aninterbody spacer, or intervertebral implant, can be inserted into thecavity created where the intervertebral disc was removed to helpmaintain height of the spine and/or restore stability to the spine. Aninterbody spacer may also provide a lordotic correction to the curvatureof the spine. An example of an interbody spacer that has been commonlyused is a fixed dimension cage, which typically is packed with boneand/or bone-growth-inducing materials.

One drawback of spacers known in the art is that they can be of fixedheight and/or footprint, and may not provide adequate or precise heightrestoration and support between affected vertebral bodies. Fixed sizecages can also require more invasive procedures for implantation, due totheir necessarily larger pre-implantation size. Accordingly, there is aneed for an intervertebral implant which can be inserted along one axis,and be expanded both horizontally and vertically to provideintervertebral support and lordotic correction.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be best understood byreference to the drawings, wherein like parts are designated by likenumerals throughout. It will be readily understood that the componentsof the invention, as generally described and illustrated in the Figuresherein, could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theembodiments of the apparatus, system, and method, as represented inFIGS. 1 through 27E, is not intended to limit the scope of theinvention, as claimed in this or any other application claiming priorityto this application, but is merely representative exemplary of exemplaryembodiments of the invention. Embodiments of the invention are depictedin the following figures:

FIG. 1A is an isometric view of an embodiment of an interbody spacer ina collapsed configuration, and FIG. 1B is an end view of the interbodyspacer of FIG. 1B;

FIG. 2A is an isometric view of the interbody spacer of FIG. 1 in apartially expanded configuration in which the spacer is expandedhorizontally, and FIG. 2B is a top down view of the interbody spacer ofFIG. 2A absent an upper body;

FIG. 3A is an isometric view of the interbody spacer of FIG. 1 in afully expanded configuration in which the spacer is expandedhorizontally and vertically, and FIG. 3B is a top down view of theinterbody spacer of FIG. 3A absent an upper body;

FIG. 4 is an exploded isometric view of the interbody spacer of FIG. 1;

FIG. 5A is a side view of an upper body of the interbody spacer of FIG.1, FIG. 5B is an isometric view of a lower body of the interbody spacerof FIG. 1, and FIG. 5C is a side cross-sectional view of the upper andlower bodies of FIGS. 5A and 5B;

FIG. 6A is a top down view of a first end body of the spacer of FIG. 1,FIG. 6B is a side view of the end body of FIG. 6A, and FIG. 6C is aninner side view of the of the end body of FIG. 6A;

FIG. 7A is a top down view of a second end body of the spacer of FIG. 1,FIG. 7B is a side view of the end body of FIG. 7A, and FIG. 7C is aninner side view of the of the end body of FIG. 6A;

FIG. 8 is a side cross-sectional view of the spacer of FIG. 1 in thecollapsed configuration;

FIG. 9 is a side cross-sectional view of the spacer of FIG. 1 in thehorizontally expanded configuration, taken along section line A-A inFIG. 2B;

FIG. 10 is a side cross-sectional view of the spacer of FIG. 1 in thehorizontally and vertically expanded configuration, taken along sectionline B-B in FIG. 3B;

FIG. 11 is a isometric view of another embodiment of an interbody spacerin an expanded configuration;

FIG. 12A is a top down view of the interbody spacer of FIG. 11 in acollapsed configuration; FIG. 12B is a side view of the interbody spacerof FIG. 11 in a collapsed configuration;

FIG. 13A is a bottom view of the interbody spacer of FIG. 11 in theexpanded configuration; FIG. 13B is a first end view of the interbodyspacer of FIG. 11 in the expanded configuration;

FIG. 14 is an isometric exploded view of the interbody spacer of FIG.11;

FIG. 15 is a side cross-sectional view of the spacer of FIG. 11 in thehorizontally and vertically asymmetrically expanded configuration, takenalong section line C-C in FIG. 13A;

FIG. 16A is an isometric view of an alternative embodiment of aninterbody spacer in a collapsed configuration; FIG. 16B is a back endview of the interbody spacer of FIG. 16A;

FIG. 16C is an isometric view of the interbody spacer of FIG. 16A in alaterally expanded configuration; FIG. 16D is a back end view of theinterbody spacer of FIG. 16C; FIG. 16E is an isometric view of theinterbody spacer of FIG. 16A in a laterally and vertically expandedconfiguration; and FIG. 16F is a back end view of the interbody spacerof FIG. 16E;

FIG. 17 is an isometric exploded view of the interbody spacer of FIG.16A;

FIG. 18A is a top down view of a link body of the interbody spacer ofFIG. 16A; FIG. 18B is a bottom up view of the link body of FIG. 18A;FIG. 18C is a side view of the link body of FIG. 18A; and FIG. 18D is anopposite side view of the link body of FIG. 18C;

FIG. 19A is an interior side view of a lower support body of theinterbody spacer of FIG. 16A; FIG. 19B is a top down view of the lowersupport body of FIG. 19A; FIG. 19C is an isometric view of the lowersupport body of FIG. 19A; and FIG. 19D is an cross-sectional view of thelower support body of FIG. 16A taken along line D-D in FIG. 19B and across-sectional view of an upper support body of the interbody spacer ofFIG. 16A taken along an approximate midline of the upper support body;

FIG. 20A is a top down view of a first end body of the interbody spacerof FIG. 16A; FIG. 20B is a side view of the first end body of FIG. 20A;FIG. 20C is an isometric view of the first end body of FIG. 20A; FIG.20D is an inner side view of the first end body of FIG. 20A; and FIG.20E is an outer side view of the first end body of FIG. 20A;

FIG. 21A is an outer side view of a second end body of the interbodyspacer of FIG. 16A; FIG. 21B is an inner side view of the first end bodyof FIG. 21A; FIG. 21C is an isometric view of the first end body of FIG.21A; FIG. 21D is a side view of the first end body of FIG. 21A; and FIG.21E is an top down view of the first end body of FIG. 21A;

FIG. 22A is a top down partial view of the interbody spacer of FIG. 16A,with two upper support bodies absent to show the assemblage of the endbodies, links, and lower support bodies; and FIG. 22B is across-sectional view of the interbody space of FIG. 16A, taken alongline E-E in FIG. 22A;

FIG. 23A is a top down partial view of the interbody spacer of FIG. 16B,with two upper support bodies absent to show the assemblage of the endbodies, links, and lower support bodies; and FIG. 23B is across-sectional view of the interbody space of FIG. 16B, taken alongline F-F in FIG. 23A;

FIG. 24A is a top down partial view of the interbody spacer of FIG. 16C,with two upper support bodies absent to show the assemblage of the endbodies, links, and lower support bodies; and FIG. 24B is across-sectional view of the interbody space of FIG. 16C, taken alongline G-G in FIG. 23A;

FIG. 25A is an isometric view of an embodiment of an asymmetricalexpandable interbody spacer in a collapsed configuration, the interbodyspacer having an integrated surface angle for spinal correction; FIG.25B is an isometric view of the spacer of FIG. 25A in a laterally andvertically expanded configuration; FIG. 25C is a side view of the spacerof FIG. 25A in a laterally expanded configuration, showing the surfaceangle for spinal correction; FIG. 25D is an opposite side view of thespacer of FIG. 25C; and FIG. 25E is a back end view of the spacer ofFIG. 25C;

FIG. 26A is an isometric view of another embodiment of an asymmetricalexpandable interbody spacer in a collapsed configuration, FIG. 26B is anisometric view of the spacer of FIG. 26A in a laterally expandedconfiguration; and FIG. 26C is an isometric view of the spacer of FIG.25A in a laterally and vertically expanded configuration; and

FIG. 27A is a top down view of the spacer of FIG. 26A; FIGS. 27B is atop down view of the space of FIG. 26B; FIG. 27C is a top down partialview of the spacer of FIG. 26C with two upper support bodies absent toshow the assemblage of the end bodies, links, and lower support bodies;FIG. 27D is a side view of the spacer of FIG. 27C; and FIG. 27 E is aback end view of the spacer of FIG. 27C.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Disclosed herein are interbody spacers which are expandable from acollapsed or closed configuration to an expanded or open configurationby means of horizontal and/or vertical expansion. Expansion of thespacer may take place in situ after placement in between two vertebralbodies, and bone graft or other materials may be inserted into the openspacer during or after placement and expansion. The impetus to expandthe spacer may be provided by a single application of axial force alonga longitudinal spacer axis. The intervertebral spacers disclosed hereininclude symmetrical and asymmetrical embodiments, and embodiments whichmay expand symmetrically and/or asymmetrically. One or more embodimentsmay include means for lordotic correction. Lordotic correction may beprovided inherently by angulation of spacer body surfaces, and/or byasymmetrical spacer expansion.

Referring to FIGS. 1A through 3B, an interbody spacer 100, which mayalso be referred to as a device, cage, insert, or implant, is expandablefrom the collapsed, or compact configuration seen in FIG. 1A, along afirst axis and a second axis. The spacer 100 has a lengthwise spaceraxis 102, and may be expandable in a first direction along a first axis104 which may be a horizontal or lateral expansion axis, to ahorizontally expanded configuration seen in FIG. 2A. The device may befurther expanded in a second direction along a second axis 106, whichmay be a vertical expansion axis, to the horizontally and verticallyexpanded configuration seen in FIG. 3. Axes 104, 106 may beperpendicular to each other and perpendicular to spacer axis 102. Whenimplanted between two vertebral bodies in a portion of a spine, thespacer 100 is expandable horizontally, or substantiallyanterior-posteriorly, along the first axis 104, and vertically, orcephalad-caudally, along the second axis 106. A single axial forceacting along the spacer axis 102 may provide the expansion force forboth the horizontal and vertical expansion. The spacer 100 may bebilaterally symmetrical with respect to a vertical plane extending alongspacer axis 102, and may be bilaterally symmetrical with respect to ahorizontal plane extending along spacer axis 102. In an alternateembodiment, the spacer may be expandable medial-laterally. In otherembodiments, the spacer may be asymmetrically expandableanterior-posteriorly, cephalad-caudally, and/or medial-laterally. It isunderstood any one of the spacers disclosed within may also be implantednon-parallel to the sagittal plane of the vertebral bodies, in whichinstance horizontal spacer expansion may not be strictlyanterior-posterior or medial-lateral.

Referring to FIGS. 1A and 1B, the spacer 100 includes an upper surface110 and a lower surface 112 separated by a first side 114 and a secondside 116. A first end 118 and a second end 120 are separated by theupper and lower surface and first and second sides.

Referring to FIGS. 1A through 4, the interbody spacer comprises a set ofbodies pivotably linked together, allowing the bodies to articulaterelative to one another. A first support member 130 includes a firstupper body 132 and a first lower body 134. A second support member 140includes a second upper body 142 and a second lower body 144. A firstend body 150 is pivotably linked to the first and second support members130, 140 toward the first end 118, and a second end body 152 ispivotably linked to the first and second support members 130, 140 towardthe second end 120. The upper and lower bodies may be mirror images ofone another, as may the first and second support members. In analternate embodiment the first and second support members 130 and 140may be of differing proportions and/or configuration in order to provideasymmetric expansion.

Turning to FIG. 4, additional components of the spacer 100 may be seen.A plurality of links 160, 162, 164, 166 link the support members 130,140 to the end bodies 150, 152. Link 160 joins first end body 118 toupper and lower bodies 132, 134, via a pin 170. Link 162 joins secondend body 120 to the opposite ends of upper and lower bodies 132, 134,via a pin 172. Similarly, link 164 joins first end body 118 to upper andlower bodies 142, 144, via a pin 174. Link 166 joins second end body 120to the opposite ends of upper and lower bodies 142, 144 via a pin 176.

Each link 160, 162, 164, 166 includes a pivot member which is generallyshaped as a spool, in the embodiment depicted. These links mayalternately take on other shapes such as cylinders with sloped ends ortwo generally spherical ends connected by a post. Link 160 is describedherein in further detail, but it is appreciated that the descriptionalso applies to the other links 162, 164, 166. Link 160 includes a linkbody 180, which is aligned along a horizontal plane which may beparallel to spacer axis 102 when the spacer is properly assembled. Anupper support block 181 is on an upper side of link body 180, opposite alower support block 182 on the lower side of the link body. An open bore183 is formed on link body 180 for rotatably receiving pin 170. Alocking recess 187 may be formed on the link body to facilitate lockingwith one of the end bodies, to prevent unintended movement out of thehorizontally expanded configuration. A channel 189 may be recessed intothe link body to provide passage for instrumentation and/or allograft orother materials. Opposite the open bore, a spool 184 includes acylindrical stem 185 which supports an upper head 186 and a lower head188. Other embodiments may include non-cylindrical stems. Upper head 186includes an upper ramped surface 190, and lower head 188 includes alower ramped surface 192. Upper and lower ramped surfaces 190, 192 arenon-parallel with respect to each other. Each ramped surface 190, 192may be angled in a range of 0° to 60° relative to the horizontal planeof the link body 180. In an exemplary embodiment, the ramped surfacesmay be at an angle of 20° to the horizontal plane of the link body 180.Each head 186, 188 may be of a larger diameter than the cylindrical stem185. A chamfer 194 may encircle the upper head 186 adjacent the rampedsurface 190; similarly a chamfer 196 may encircle the upper head 188adjacent the ramped surface 192. The chamfers 194, 196 may act as guidesurfaces as the spacer 100 transitions from horizontal expansion tovertical expansion.

Support member 130 includes upper and lower bodies 132, 134. First lowerbody 134 is described herein in further detail, but it is appreciatedthat the description also applies to the second lower body 144, whichmay be a mirror image of first lower body 134. Referring to FIGS. 3B,5A-5C, each upper and lower body is generally elongated and rectangularin footprint, although their perimeters and edges may be rounded topromote easier insertion into the intervertebral space and to preventdamage to surrounding tissues. Depressed into the upper face 200 are afirst receptacle 208 and a second receptacle 210. The first receptacle208 includes a cylindrical portion 212 and a ramped portion 214 with aramped lower surface. An undercut 216 is formed in the ramped portion214 away from the cylindrical portion and toward the center of the lowerbody. The second receptacle 210 may be a mirror image of the firstreceptacle, and includes a cylindrical portion 222, a ramped portion 224with a ramped lower surface, and an undercut 226. Each ramped surfacemay be angled in a range of 0° to 60° relative to the horizontal planeof the lower body 134. In an exemplary embodiment, the ramped surfacesmay be at an angle of 20° to the horizontal plane of the lower body 134.A blind bore 228 extends into the body 134 between the receptacles.Recesses 230, 232 in the upper face 200 on opposite ends of the lowerbody 134, receive portions of links 160, 162 when the implant is in thecollapsed configuration as in FIG. 1A.

Upper body 132 is described herein in further detail, but it isappreciated that the description also applies to the other upper body142, which may be a mirror image of upper body 132. Upper body 132includes an upper face 240 and a lower face 242, separated by an outerface 244 and an inner face 246. Depressed into the lower face 242 is afirst receptacle 248 and a second receptacle 250. The first receptacle248 includes a cylindrical portion 252 and a ramped portion 254 with aramped upper surface. The ramped portions 214, 224, 254, 264 may also bereferred to as expansion slots. An undercut 256 is formed in the rampedportion 254 away from the cylindrical portion and toward the center ofthe upper body. Each ramped surface may be angled in a range of 0° to60° relative to the horizontal plane of the upper body 132. In anexemplary embodiment, the ramped surfaces may be at an angle of 20° tothe horizontal plane of the upper body 132. The second receptacle 250may be a mirror image of the first receptacle, and includes acylindrical portion 262, a ramped portion 264, and an undercut 266. Apeg 268 protrudes from the body 132 between the receptacles.

When the spacer 100 is properly assembled, pegs 268 are received inblind bores 228 to provide proper alignment of upper and lower bodies,provide support in the collapsed configuration, and provide stability.Recesses 270, 272 in the lower face 242 on opposite ends of the upperbody 132 receive portions of links 160, 162 when the implant is in thecollapsed configuration as in FIG. 1A. Upper face 240 of upper body 132,and lower face 242 of lower body 134 may be exteriorly facing when thespacer 100 is properly implanted, and may include ridges, furrows,points, surface roughening, or other surface treatments to facilitateengagement with the adjacent vertebral bodies. In an alternateembodiment the first and second support members 130 and 140 may be ofdiffering length, proportion and/or configuration, and one of themembers may not expand vertically in order to provide asymmetricvertical expansion.

Referring to FIGS. 6 and 7, further details of the end bodies are shown.First end body 150 includes a leading surface 280 and an inner side 282.In the embodiment shown, the leading surface 280 is smooth andbullet-nosed with a leading edge 284 to facilitate insertion into theintervertebral space. The inner side 282 includes connection features286, 288 for connection to links 162, 166 via pins 172, 176 to form tworotatable end joints 290. It is appreciated that other connectionfeatures and/or joint types could be used to achieve the same resultwithin the scope of the invention. In the embodiment shown, each endjoint 290 may rotate open up to 60° to provide horizontal expansion. Inother embodiments, the end joint may rotate in a range from 20° to 100°.A threaded bore 292 extends partially into the first end body 150 fromthe inner side 282, to provide connection with insertion and deploymentinstrumentation. The threaded bore 292 may be perpendicular to therotation axes of the connection features 286, 288. Stop faces 294, 296may prevent over-expansion of device 100 by interaction with links 162,166. The entrance to bore 292 may be further recessed into inner side282 than are the stop faces.

Second end body 152 includes an exterior face 300 and an inner side 302.The exterior face 300 may include a protruding boss 304, which mayfacilitate engagement with instrumentation. A bore 305 extends throughthe second end body 152 between and in communication with the exteriorface 300 and the inner side 302. The bore 305 may be non-tapped and mayallow access for instrumentation. A lip 307, visible in FIG. 1B,encircles bore 305 near the inner side 302 and may engage withinstrumentation. In other embodiments, the bore 305 may be threaded orinclude other features for engagement with instrumentation. The innerside 302 includes connection features 306, 308 for connection to links160, 164 via pins 170, 174 to form rotatable end joints 290. The bore305 may be perpendicular to the rotation axes of the connection features306, 308. Each connection feature 306, 308 may include a locking featureto hold the device 100 open once it has been horizontally expanded.Locking features 310, 312 are ridges formed on an outer surface of theconnection features 306, 308, respectively. When the device 100 ishorizontally expanded, the locking feature 310 may snap into the lockingrecess 187 on link 160 to hold the device 100 horizontally open in arigid open position and prevent unintended collapse into the collapsedconfiguration. It is appreciated that similar locking features couldalso be included on first end body 150, or that other types of tabs,latches, inserts, set screws, or locking features could be included onthe device to keep the device rigidly locked open and preventunintentional collapse. Stop faces 314, 316 may prevent over-expansionof device 100 by interaction with links 160, 164.

In a method of use, a patient may be prepared by performing a discectomybetween two target intervertebral bodies. A lateral or anterior approachmay be used. The vertebral bodies may be distracted, and spacer 100mounted on an appropriate insertion instrument and inserted into theprepared space in between the vertebral bodies. In one example, thespacer 100 is mounted on an insertion rod with a threaded rod tipinserted through bore 305, through channels 189 and threaded into bore292. Another portion of the insertion instrument may latch securely onto second end body 152. The spacer 100 may be inserted with first end118 leading; leading edge 284 and smooth leading surface 280 may easethe insertion step. If necessary, force may be applied to the instrumentand spacer 100 to facilitate insertion; boss 304 and second end body 152are intended to withstand and transmit the insertion forces. Asinsertion commences, the spacer 100 is in the collapsed, compact orclosed configuration seen in FIGS. 1A and FIG. 8. Before insertion iscomplete, the expansion of the spacer 100 may begin.

After or during insertion between the vertebral bodies, the insertioninstrument may be manipulated to urge horizontal expansion of the spacer100, to attain the expanded configuration seen in FIG. 2A. For example,the rod member of an insertion instrument may be rotated or ratcheted toprovide an axial force along axis 102 to urge first end body 150 andsecond end body 152 toward one another, decreasing the distance betweenthem. The axial force urges joints 290 to pivot open, pushing first andsecond support members 130, 140 outward and away from one another alongaxis 104, into the horizontally expanded configuration seen in FIGS. 2A,2B and 9. During this horizontal expansion, links 160, 162, 164, 166pivot outward, or laterally relative to axis 102.

FIG. 8 depicts the collapsed configuration. Spools 184 are received inthe cylindrical portions 212, 222, 252, 262 of the first and secondreceptacles of the upper 142 and lower 144 bodies. The upper and lowerramped surfaces 190, 192 of the links are oriented such that the spoolsare prevented from moving into the ramped portions, or expansion slots,214, 224, 254, 264. Vertical expansion cannot be achieved while thespacer 100 is in the collapsed configuration.

FIG. 9 depicts the horizontally expanded configuration. Due to rotationof the joints, spools 184 have rotated to the point where the upper 190and lower 192 ramped surfaces are now parallel with the expansion slots214, 224, 254, 264. The angle of the upper ramped surface 190 of eachspool matches the angle of the upper ramped surface of the expansionslot 254, 265 with which it is aligned. The angle of the lower rampedsurface 192 of each spool matches the angle of the lower ramped surfaceof the expansion slot 214, 224 with which it is aligned. The chamferedguide surfaces 194, 194 may facilitate alignment of the upper and lowerramped surfaces with the expansion slots. With reference to FIG. 2B,locking features 310, 312 are received in locking recesses 187 to lockthe spacer in the horizontally expanded configuration. The stop faces294, 296, 314, 316 on the end bodies 150, 152 prevent overexpansion ofthe device. An inner chamber 320 is bounded by a horizontal perimeterformed by the support members 130, 140 and end bodies 150, 152interspersed with links 160, 162, 164, 166.

Further axial force along axis 102, which may be attained by furtherrotation of a rod portion of the insertion instrument, urges the spools184 into the expansion slots, pushing the upper 132, 142 and lower 134,144 bodies away from one another along axis 106, into the verticallyexpanded configuration seen in FIGS. 3A and 10. During verticalexpansion, ramped surfaces 190 may slide against the upper rampedsurfaces of the expansion slots 254, 264, and the ramped surfaces 192may slide against the lower ramped surfaces of the expansion slots 214,224. FIG. 10 depicts the horizontally and vertically expandedconfiguration of the spacer 100. Spools 184 have been urged toward oneanother within in each of the upper and lower bodies into the expansionslots 214, 224, 254, 264. The upper and lower head portions 186, 188 arereceived in the expansion slots, and into the undercuts 216, 226, 256,266. Ramped surfaces 190 may be flush against the upper ramped surfacesof the expansion slots 254, 264, and the ramped surfaces 192 may beflush against the lower ramped surfaces of the expansion slots 214, 224.The height of the inner chamber 320 is increased with the verticalexpansion, but the footprint or horizontal perimeter may remainconstant. The inner boundaries of the expansion slots provide a physicalstop to prevent any further vertical expansion.

In other embodiments of the disclosure, the spacer could be expanded ononly one side; for example support member 130 could be horizontallyand/or vertically expanded while support member 140 remains in itscollapsed position, or vice versa. In another embodiment, anon-expanding support member such as 140 could be solid. This type ofasymmetrical expansion could provide a lordotic or kyphotic correction.

An alternative embodiment of the disclosure is shown in FIGS. 11-15.Spacer 400 may be horizontally and/or vertically expanded to provide anasymmetric construct. As shown in FIGS. 13A and 13B, when fullyexpanded, spacer 400 may be asymmetric relative to at least lengthwisespacer axis 402. Horizontal expansion along first axis 404 in a firstdirection may be asymmetric relative to spacer axis 402 and second axis406. Vertical expansion along axis 406 in a second direction may beasymmetric relative to spacer axis 402 and first axis 404. Like spacer100, an expansion instrument may be deployed to provide an axial forcealong axis 402, through which horizontal (or lateral) expansion firstoccurs along axis 404, followed subsequently by vertical expansion alongaxis 406. The expansion along axis 404 may be asymmetrical in that oneside of the spacer, relative to spacer axis 402, moves a greaterdistance than the opposite side of the spacer relative to spacer axis402. Similarly, the expansion along axis 406 may be asymmetrical in thatone side of the spacer, relative to spacer axis 402, moves a greaterdistance vertically than the opposite side of the spacer relative tospacer axis 402. The degree of vertical expansion may be less than,equal to, or greater than the degree of horizontal expansion. In anexemplary embodiment, the absolute distance of horizontal expansion maybe greater than the absolute distance of vertical expansion.

Referring to FIGS. 12A, 12B, 13A and 13B, the spacer 400 includes anupper surface 410 and a lower surface 412 separated by a first side 414and a second side 416. A first end 418 and a second end 420 areseparated by the upper and lower surface and first and second sides.

Referring to FIGS. 11 through 15, the interbody spacer 400 comprises aset of bodies pivotably linked together, allowing the bodies toarticulate relative to one another. A first support member 430 includesan upper body 432 and a lower body 434. A second support member 440includes a side body 442 and first and second pivot bodies 444, 446. Thepivot bodies 444, 446 may be mirror images of one another. A first endbody 450 is pivotably linked to the first and second support members430, 440 toward the first end 418, and a second end body 452 ispivotably linked to the first and second support members 430, 440 towardthe second end 420. A first link 460 pivotably joins the second end body452 to the first support member 430, and a second link 462 pivotablyjoins the first end body 450 to the first support member 430. The firstand second links 460, 462 may be mirror images of one another. Similarto spacer 100, a plurality of pins 470 pivotably connect the first andsecond pivot bodies 444, 446 and the first and second links 460, 462with the end bodies 450, 452.

Turning to FIGS. 14 and 15, additional detail of spacer 400 is shown.Link 462 is described in additional detail; it is understood that thedescription of link 462 applies to link 460, which is a mirror image.Link 462 includes a link body 480, which is aligned along a horizontalplane which may be parallel to spacer axis 402 when the spacer isproperly assembled. An upper support block 481 is on an upper side oflink body 480, opposite a lower support block 482 on the lower side ofthe link body. An open bore 483 is formed on link body 480 for rotatablyreceiving link 470. In some embodiments, a locking recess may be formedon the link body to facilitate locking with one of the end bodies, toprevent unintended movement out of the horizontally expandedconfiguration. A channel 489 may be recessed into the link body toprovide passage for instrumentation and/or allograft or other materials.Opposite the open bore, a cylinder 484 includes an upper ramped surface490, and a lower ramped surface 492. Upper and lower ramped surfaces490, 492 are non-parallel with respect to each other. Each rampedsurface 490, 492 may be angled in a range of 0° to 60° relative to thehorizontal plane of the link body 480. In an exemplary embodiment, theramped surfaces may be at an angle of 20° to the horizontal plane of thelink body 480.

Support member 430 includes upper and lower bodies 432, 434. Referringto FIGS. 14 and 15, lower body 434 includes an upper face 500 and alower face 502, separated by an outer face 504 and an inner face 506.Lower body 434 further includes a first receptacle 508 and a secondreceptacle 510. The first receptacle 508 includes a cylindrical portion512 and a ramped portion 514 with a ramped lower surface. The secondreceptacle 510 may be a mirror image of the first receptacle, andincludes a cylindrical portion 522, a ramped portion 524 with a rampedsurface. Each ramped surface may be angled in a range of 0° to 60°relative to the horizontal plane of the lower body 434. In an exemplaryembodiment, the ramped surfaces may be at an angle of 20° to thehorizontal plane of the lower body 434. A peg 568 protrudes from thebody 434 between the receptacles.

Upper body 432 includes an upper face 540 and a lower face 542,separated by an outer face 544 and an inner face 546. Depressed into thelower face 542 are a first receptacle 548 and a second receptacle 550.The first receptacle 548 includes a cylindrical portion 552 and a rampedportion 554 with a ramped upper surface. The ramped portion may also bereferred to as an expansion slot. Each ramped surface may be angled in arange of 0° to 60° relative to the horizontal plane of the upper body432. In an exemplary embodiment, the ramped surfaces may be at an angleof 20° to the horizontal plane of the upper body 432. The secondreceptacle 550 may be a mirror image of the first receptacle, andincludes a cylindrical portion 562 and a ramped portion 564. A blindbore 528 extends into the body 434 between the receptacles. When thespacer 400 is properly assembled, peg 568 is received in blind bore 528to provide proper alignment of upper and lower bodies, provide supportin the collapsed configuration, and provide stability. Upper face 540 ofupper body 432 and lower face 502 of lower body 434 may be exteriorlyfacing when the spacer 400 is properly implanted, and may includeridges, furrows, points, surface roughening, or other surface treatmentsto facilitate engagement with the adjacent vertebral bodies.

The appearance, shape, description and function of end body 150 mayapply to end body 450. Similarly, the appearance, shape, description andfunction of end body 152 may apply to end body 452.

In the embodiment depicted in FIGS. 11-15, second support member 440includes side body 442 and first and second pivot bodies 444, 446. Inother embodiments of the invention, the second support member maycomprise more or fewer connected bodies. Second support member includesan upper exterior surface 572 and a lower exterior surface 574. Sidebody 442 includes an upper support block 580 and a lower support block582. Connection features 584, 586 are formed at opposite ends forconnection with the pivot bodies. First pivot body 444 includes an uppersupport block 590 and a lower support block 592. Connection features594, 596 are formed at opposite ends for connection with the side body442 and end body 450. A channel 598 may be recessed into the pivot bodyto provide passage for instrumentation and/or allograft or othermaterials. When the spacer 400 is properly assembled, the connectionfeatures of the pivot bodies may fit together with the connectionfeatures of the side body to provide essentially continuous unbrokenupper and lower exterior surfaces 572, 574 whether the spacer is in acompact or an expanded configuration. The upper and lower surfaces 572,574 may be essentially parallel to one another, and parallel tohorizontal axis 404; in alternate embodiments they may be non-parallel.Similar to the first support member 430, the upper and lower exteriorsurfaces of the second support 440 member may include ridges, furrows,points, surface roughening, or other surface treatments to facilitateengagement with the adjacent vertebral bodies.

Spacer 400 is expandable in the same manner as spacer 100, and thedescription of expansion of spacer 100 applies to spacer 400. A singleaxial force along axis 402 may expand the o spacer first horizontallyand then vertically. During horizontal, or lateral, expansion, first endbody 450 is drawn toward second end body 452, which urges side body 442and first support member 430 and to move away from one another andperpendicularly away from spacer axis 402. This horizontal expansion isasymmetrical, as side body 442 moves a greater distance away from spaceraxis 402 than does first support member 430, as is clearly shown in FIG.13A. An inner chamber 520 is bounded by a horizontal perimeter formed bythe support members 430, 440, end bodies 450, 452 and links 460, 462.During horizontal or lateral expansion, cylinders 484 of links 460, 462pivot so that at the furthest extent of horizontal expansion, the rampedsurfaces 490, 492 of the links are aligned with the upper and lowerramped surfaces of the receptacles 548, 550, permitting verticalexpansion to commence. During the vertical expansion, lower body 432 isurged away from upper body 434, resulting in an asymmetrically expandedconfiguration in which the first side 414 and first support member 430of the spacer 400 is taller than the second side 416 and second supportmember 440 relative to the first axis 404, as is clearly shown in FIG.13B. The asymmetrical vertical expansion may be used to provide alordotic, kyphotic, scoliotic or other type of vertebral heightcorrection.

FIGS. 16A-24B illustrate another embodiment of an intervertebral spacerwhich may be horizontally and vertically expanded. Interbody spacer 600,which may also be referred to as a device, cage or implant, isexpandable from the collapsed, or compact configuration seen in FIG.16A, along a first axis and a second axis. The spacer 600 has alongitudinal spacer axis 602, and may be expandable in a first directionalong a first axis 604 which may be a horizontal or lateral expansionaxis, to a horizontally expanded configuration seen in FIG. 16B. Thedevice may be further expanded in a second direction along a second axis606, which may be a vertical expansion axis, to the horizontally andvertically expanded configuration seen in FIG. 16C. Axes 604, 606 may beperpendicular to each other and perpendicular to spacer axis 602. Whenimplanted between two vertebral bodies in a portion of a spine, thespacer 600 is expandable laterally along the first axis 604, andvertically, or cephalad-caudally, along the second axis 606. A singleaxial force acting along the spacer axis 602 may provide the expansionforce for both the horizontal and vertical expansion. The spacer 600 maybe bilaterally symmetrical with respect to a vertical plane extendingalong spacer axis 602, and may be bilaterally symmetrical with respectto a horizontal plane extending along spacer axis 602.

Referring to FIGS. 16A-16C, the spacer 600 includes an upper surface 610and a lower surface 612 separated by a first side 614 and a second side616. A first or nose end 618 and a second or back end 620 are separatedby the upper and lower surface and first and second sides. The interbodyspacer 600 comprises a set of bodies pivotably linked together, allowingthe bodies to articulate relative to one another. A first support member630 includes a first upper body 632 and a first lower body 634. A secondsupport member 640 includes a second upper body 642 and a second lowerbody 644. A first end body, or nose 650 is pivotably linked to the firstand second support members 630, 640 toward the first end 618, and asecond end body or rear body 652 is pivotably linked to the first andsecond support members 630, 640 toward the second end 620. The upper andlower bodies may be mirror images of one another, as may the first andsecond support members. As seen in FIG. 16C, a locking screw 654prevents unintentional movement of the spacer 600 from the laterally andvertically expanded configuration. The locking screw 654 may providesupplementary or final locking of the spacer.

Referring to FIG. 17, additional components of the spacer 600 may beseen. A plurality of links 660, 662, 664, 666 link the support members630, 640 to the end bodies 650, 652. Link 660 joins first end body 618to upper and lower bodies 632, 634, via a pin 670. Link 662 joins secondend body 620 to the opposite ends of upper and lower bodies 632, 634,via a pin 672. Similarly, link 664 joins first end body 618 to upper andlower bodies 642, 644, via a pin 674. Link 666 joins second end body 620to the opposite ends of upper and lower bodies 642, 644 via a pin 676.

Each link 660, 662, 664, 666 includes a pivot member which is generallyshaped as a spool, in the embodiment depicted. The pivot members mayalternately take on other shapes such as cylinders with sloped ends ortwo generally spherical ends connected by a post. Link 660 is describedherein in further detail, but it is appreciated that the descriptionalso applies to the other links 662, 664, 666. Link 660 includes a linkbody 680, which is aligned along a horizontal plane which may beparallel to spacer axis 602 when the spacer is properly assembled. Linkbody 680 extends between and connects a link first end 681 to a linksecond end 682. An open bore 683 is formed in the link first end 681 forrotatably receiving pin 670. Beveled surfaces 691, 693 may be formed onopposite faces of the link first end 681. A first stop surface 667 isformed on the link body which meets with a stop surface on one of theend bodies during spacer expansion, to limit lateral expansion of thespacer 600 and prevent over-expansion. A second stop surface 669 isformed on the link body which meets with a stop surface on one of theend bodies in the fully collapsed configuration. A concave channel 689may be recessed into the link to provide passage for instrumentationand/or allograft or other materials. In other spacer embodiments, one ormore links may be free of stop surfaces.

Opposite the link first end 681, the spool-shaped link second end 682comprises a stem portion 685 which supports an upper head 686 and alower head 688. In the embodiment shown, the stem portion 685 isnon-circular; the faceted or squared-off shape of the stem between theheads prevents additional axial rotation of the second end 682 once thespacer 600 is in the laterally expanded configuration. Upper head 686includes an upper ramped surface 690, and lower head 688 includes alower ramped surface 692. Upper and lower ramped surfaces 690, 692 arenon-parallel with respect to each other. Each ramped surface 690, 692may be angled in a range of 0° to 60° relative to the horizontal planeof the link body 680 between the first and second ends. In an exemplaryembodiment, the ramped surfaces may be at an angle of 20° to thehorizontal plane of the link body 680. Each head 686, 688 may be of alarger diameter than the stem 685. A chamfer 694 may encircle the upperhead 686 adjacent the ramped surface 690; similarly a chamfer 696 mayencircle the lower head 688 adjacent the ramped surface 692. The linkfirst end 681 may include similar chamfers. The chamfers 694, 696 mayact as guide surfaces as the spacer 600 transitions from horizontalexpansion to vertical expansion. In addition to the chamfer, a bevel 695may be formed on upper head 686, and a corresponding bevel 697 may beformed on lower head 688; other embodiments may lack the bevels.

With reference to FIGS. 17, and 19A-D, support member 630 includes upperand lower bodies 632, 634. First lower body 634 is described herein infurther detail, but it is appreciated that the description may alsoapply to the second lower body 644, and also upper bodies 632, 642, asall four bodies may be identical in an embodiment except for theirpositional arrangement with each other and other spacer elements. Eachupper and lower body is generally elongated between a first end 701 anda second end 703, and has generally rounded perimeters and edges. Lowerbody 634 includes an upper face 700 and a lower face 702, separated byan outer face 704 and an inner face 706. Depressed into the upper face700 are a first receptacle 708 and a second receptacle 710. The firstreceptacle 708 includes a first recessed portion 712 which includes aflat lower surface 713 and a second recessed portion 714 with a rampedlower surface 715. A first constriction 709 may be formed in the upperface 700 between the first and second recessed portions 712, 714 of thefirst receptacle. An undercut 716 is formed in the perimeter of thereceptacle 708. A ramp 717 occupies a portion of the first recessedportion 712 and extends toward the second recessed portion 714. Aretention feature 718, which in the embodiment shown is a raised lip, ispositioned between the first and second recessed portions 712, 714,creating a pocket around the second recessed portion 714.

The second receptacle 710 may be a mirror image of the first receptacle,and includes a first recessed portion 722 which includes a flat lowersurface 723 and a second recessed portion 724 with a ramped lowersurface 725; the receptacle 710 further includes an undercut 726 and aretention feature 728. A second constriction 711 may be formed in upperface 700 between the first and second recessed portions 722, 724 of thesecond receptacle 710. A ramp 727 occupies a portion of the firstrecessed portion 722 and slopes toward the second recessed portion 724.Each ramp may be angled in a range of 0° to 60° with respect to thehorizontal plane of the lower body 634. In an exemplary embodiment, theramps may be at an angle of 20° with respect to the horizontal plane ofthe lower body 634. A blind bore 728 extends into the body 634 betweenthe receptacles. The first recessed portions 712, 722 extend deeperwithin the support body than do the second recessed portions 714, 724.

When the spacer 600 is in the collapsed and laterally expandedconfigurations as in FIGS. 21A and 22A, a link second end 682 isreceived in the first recessed portion 712. After vertical expansion asin FIG. 23A, the link second end 682 is received in the second recessedportion 714. The retention feature 718 can serve as a provisionallocking structure, by prohibiting movement of the link second end fromthe second recessed portion 714 back to the first recessed portion 712,thus preventing unintentional vertical collapse of the spacer 600 beforeinsertion of the locking screw 654 or other locking member.

First upper body 632 is described herein in further detail, but it isappreciated that the description also applies to the second upper body642, which may be a mirror image of upper body 632. Referring to FIGS.17 and 19D, upper body 632 extends between a first end 741 and a secondend 743, and includes an upper face 740 and a lower face 742, separatedby an outer face 744 and an inner face 746. Depressed into the lowerface 742 is a first receptacle 748 and a second receptacle 750. Thefirst receptacle 748 includes a first recessed portion 752 having a flatupper surface 753 and a second recessed portion 754 with a ramped uppersurface 755. The second recessed portion may also be referred to as anexpansion slot. An undercut 756 is formed in the second recessed portion754 away from the first recessed portion and toward the center of theupper body. A ramp 757 occupies a portion of the first recessed portion752 and slopes toward the second recessed portion 754. A retentionfeature 758 is positioned between the first and second recessed portions752, 754, creating a pocket around the second recessed portion 754. Eachramp surface may be angled in a range of 0° to 60° with respect to thehorizontal plane of the upper body 632. In an exemplary embodiment, theramped surfaces may be at an angle of 20° with respect to the horizontalplane of the upper body 632. The second receptacle 750 may be a mirrorimage of the first receptacle, and includes a first recessed portion 762having a flat surface 763, a second recessed portion 764 having a rampedsurface 765, and an undercut 766. A ramp 767 occupies a portion of thefirst recessed portion 762 and slopes toward the second recessed portion764. A retention feature 778 is positioned between the first and secondrecessed portions 762, 764, and a blind bore 771 is recessed into thelower surface 742.

In one or more embodiments, additional or alternate retention featuresmay be included to provide locking which prevents movement of the linksecond end back from the second recessed portion back toward the firstrecessed portion. In an embodiment, at least one link head 686, 688 mayinclude a raised bump, and at least one second recessed portion 714,724, 754, 764 may include an indentation in its respective upper orlower surface. When vertical expansion is achieved, the bump is receivedin the indentation, providing provisional locking. In an embodiment, thelocations of the bumps and indentations may be reversed. In anotherembodiment, a detent feature may project between one of more of thelinks and one or more of the upper and lower bodies to provideprovisional locking. In another embodiment, a detent feature may projectbetween one of more of the end bodies and one or more of the upper andlower bodies to provide provisional locking. In another embodiment, atleast one of the upper and lower support bodies may include a flatsegment at the end of the ramp 717, 727, 757, 767 toward the secondrecessed portion; in the vertically expanded configuration the linksecond ends would rest upon the flat segment after moving from the firstrecessed portion to the second recessed portion.

When the spacer 600 is properly assembled, a peg 768 is received in theblind bores 728, 771 of first lower body 634 and first upper body 632and similarly second bodies 642, 644 to provide proper alignment of theupper and lower bodies, provide support in the collapsed configuration,and provide stability. Recesses 752, 762 in the lower face 742 onopposite ends of the upper body 632 receive portions of links 660, 662when the implant is in the collapsed configuration as in FIG. 16A. Aplurality of assembly pins 776 extend between the inner and outer facesof the lower and upper bodies and cooperate with undercuts 777 in thelinks to secure the spacer assemblage while permitting spacer expansion.Each peg 768 may be further secured to its respective lower and upperbodies by one or more capture pins 778, which extend through therespective body and into an elongated slot 769 on the peg 768 to retainthe peg 768 in the blind bore 728 or 771, while permitting verticalexpansion. In this or another embodiment, one or more detent featurescould project into the blind bore 728 or 771 after vertical expansion,to prevent unintentional collapse of the spacer.

Upper face 740 of upper body 632, and lower face 702 of lower body 634may be exteriorly facing when the spacer 600 is properly implanted, andmay include ridges, furrows, teeth, points, surface roughening, or othersurface treatments to facilitate engagement with the adjacent vertebralbodies. In an alternate embodiment the first and second support members630 and 640 may be of differing length, proportion and/or configuration,and one of the members may not expand vertically in order to provideasymmetric vertical expansion.

Referring to FIGS. 20A-20E, first end body 650 includes an outer orleading side 780 and an inner side 782. In the embodiment shown, theleading side 780 is smooth and bullet-nosed to facilitate insertion intothe intervertebral space. A first niche 783 and a second niche 784, eachsized to receive a portion of a link, are on opposite ends of the endbody 650, opening toward the inner side 782. The end body 650 includesconnection features 786, 788 for connection to links 660, 664 via pins670, 674 to form two rotatable end joints 790. It is appreciated thatother connection features and/or joint types could be used to achievethe same result within the scope of the invention. In the embodimentshown, each end joint 790 may rotate open up to 60°. In otherembodiments, the end joints may rotate in a range from 20° to 100° . Athreaded bore 795 extends through the first end body 750 to provideconnection with insertion and/or deployment instrumentation. Thethreaded bore 795 may be perpendicular to the rotation axes of theconnection features 786, 788. A pair of first stop faces 792, 794 meetwith link stop faces 669 when the spacer 600 is collapsed. A pair ofsecond stop faces 796, 798 prevent over-expansion of device 600 bydirectly abutting with opposing stop surfaces 667 on links 660, 664 whenthe device is in the laterally expanded and vertically expandedconfigurations.

The second end body 752, which may be referred to as a back end or arear end, includes an outer side 800 and an inner side 802. The exteriorside 800 may include a protruding boss 804, which may facilitateengagement with instrumentation. A bore 805 extends through the secondend body 852 between and in communication with the exterior face 800 andthe inner side 802. The bore 805 may be non-threaded and non-circularand may allow access for instrumentation, graft insertion and lockingscrew 654. Other connection features including but not limited to posts,pins, depressions or additional bores may be present on the second endbody for engagement with instrumentation. The non-circular bore 805shape see in FIGS. 20A and 20B may allow an opening sized to acceptlarge graft pieces, but still provides points of opposing contact with ashoulder 655 of the locking screw 654. In other embodiments, the bore805 may be threaded or include other features for engagement withinstrumentation. As seen in FIGS. 17 and 24A, the inner side 802includes connection features 806, 808 for connection to links 662, 666via pins 672, 676 to form rotatable end joints 791. The bore 805 may beperpendicular to the rotation axes of the connection features 806, 808.The second end body 752 includes first and second stop surfaces. When inthe collapsed configuration, the first stop surfaces 810, 812 meet linkstop surfaces 669. When laterally expanded, the second stop surfaces814, 816 abut link stop surfaces 667, preventing unintentional excesslateral expansion of the space. It is appreciated that other stopfeatures could also be included on first or second end bodies 650, 652,or that other types of tabs, latches, inserts, set screws, or lockingfeatures could be included on the device to keep the device rigidlylocked open and prevent unintentional collapse.

The locking screw 654 includes a threaded portion 653 and a shoulder655. The threaded portion 653 may be inserted longitudinally along axis602 through rear bore 805, through chamber 820 and toward nose bore 795.The threaded portion may engage in nose bore 795, and screw shoulder 655may abut the opening of rear bore 805 to rigidly lock the configurationof the spacer.

In a method of use, a patient may be prepared by performing a discectomybetween two target intervertebral bodies. A transforaminal, posterior,lateral or anterior approach may be used. The vertebral bodies may bedistracted, and spacer 600 mounted on an appropriate insertioninstrument and inserted into the prepared space in between the vertebralbodies. In one example of the method, the spacer 600 is mounted onto aninsertion rod having a threaded rod tip which is inserted through bore805, and threaded into bore 795. Another portion of the insertioninstrument may latch securely on to second end body 652. The spacer 600may be inserted between the vertebral bodies with first end 618 leading;smooth leading surface 780 may ease the insertion step. If necessary,force may be applied to the instrument and spacer 600 to facilitateinsertion; boss 804 and second end body 852 are intended to withstandand transmit the insertion forces. As insertion commences, the spacer600 is in the collapsed, compact or closed configuration seen in FIGS.16A and FIG. 22A. Before insertion between the vertebral bodies iscomplete, the expansion of the spacer 600 may begin.

After or during insertion between the vertebral bodies, the insertioninstrument may provide the impetus to urge horizontal or lateralexpansion of the spacer 600, to attain the expanded configuration seenin FIG. 16B. For example, the rod member of an insertion instrument maybe rotated or ratcheted to provide an axial force along axis 602 to urgefirst end body 650 and second end body 652 toward one another,decreasing the distance between them.

The axial force urges joints 790, 791 to rotate open, pushing first andsecond support members 630, 640 outward and away from one another alongaxis 604, into the laterally expanded configuration seen in FIGS. 16Band 23A. During this horizontal expansion, links 660, 662, 664, 666pivot outward, or laterally relative to axis 602.

FIGS. 16A, 22A and 22B depict the collapsed configuration of spacer 600.Link second ends 682 are received in the first recessed portions 712,722, 752, 762 of the first and second receptacles of the upper 632 andlower 634 bodies. In this position, the juxtaposition and shape of thestem portion 685 of each link relative to the expansion slots 714,724,754, 764 prevent movement of the links into the expansion slots. Thus,in the embodiment shown, vertical expansion cannot be achieved while thespacer 600 is in the collapsed configuration.

FIGS. 16B, 23A and 23B depict the laterally expanded configuration ofspacer 600. Due to rotation of the joints 790 and 791, link second ends682 have rotated within first recessed portions 712, 752 and 722, 762 tothe point where the upper 690 and lower 692 ramped surfaces are nowparallel with and rest against the ramps 717, 727, 757, 767. The angleof the upper ramped surface 690 of each link second end matches theangle of the upper ramped surface 755, 765 of the expansion slot 754,764 with which it is now aligned. The angle of the lower ramped surface692 of each link second end matches the angle of the lower rampedsurface 715, 725 of the expansion slot 714, 724 with which it is nowaligned. The chamfered guide surfaces 694 and bevels 691, 693, 695, 697may facilitate alignment of the upper and lower ramped surfaces with theexpansion slots. Interaction of the stop surface 667 on each respectivelink with the stop surfaces 796, 798 on the first end body 650, and withthe stop surfaces 814, 816 on the second end body 652 preventsoverexpansion of the device. An inner chamber 820 is bounded by ahorizontal perimeter formed by the support members 630, 640 and endbodies 650, 652 interspersed with links 660, 662, 664, 666.

Upon further axial force along axis 602, which may be attained byfurther rotation of a rod portion of an insertion instrument, linksecond ends 682 of links 660, 662, 664, 666 cease rotation and are urgedto move into the expansion slots 714, 754 and 724, 764 of each of theupper and lower bodies, thus pushing the upper 632, 642 and lower 634,644 bodies away from one another along axis 606, into the verticallyexpanded configuration seen in FIGS. 16C, 24A and 24B. During verticalexpansion, upper ramped surfaces 690 mate and slide against the upperramped surfaces 755, 765 of the upper expansion slots 754, 764, and thelower ramped surfaces 692 mate and slide against the lower rampedsurfaces of the lower expansion slots 714, 724. The bevels 695, 697 oneach link may facilitate advancement of the link second ends 682 alongramps 717, 727, 757, 767 during vertical expansion of the spacer. Duringvertical expansion the distance between first and second end bodies 650,652 continues to decrease. During vertical expansion, further outwardrotation of the links is prevented by engagement of the squared-off stemportions 685 of the links with the receptacle constrictions of the upperand lower bodies.

FIG. 24B depicts the horizontally and vertically expanded configurationof the spacer 600. Spools 184 have been urged toward one another intothe upper 754, 764 and lower 714, 724 expansion slots. The upper andlower head portions 686, 688 are received in the expansion slots, andinto the undercuts 716, 726, 756, 766. Ramped surfaces 690 may be flushagainst the upper ramped surfaces of the expansion slots 754, 764, andthe ramped surfaces 692 may be flush against the lower ramped surfacesof the expansion slots 714, 724. The height of the spacer 600 and theinner chamber 820 is increased with the vertical expansion, but thefootprint or horizontal perimeter may remain constant during verticalexpansion. When vertical expansion is complete, the insertion instrumentmay be removed from the spacer. Retention features 718, 758 preventunintentional movement of the head portions out of the expansion slotsunder the increased compressive load resulting from the adjacentvertebrae bearing against the spacer 600. The retention features and thepockets created thereby may act as a provisional lockout to preserve thelateral and vertical expansion until addition of a secondary lockoutsuch as locking screw 654. The inner boundaries of the expansion slotsprovide a physical stop to prevent any further vertical expansion. Insome embodiments, a detent feature may snap or otherwise project intobore 771 above and/or bore 728 below peg 768 to prevent collapse.

In a method of the invention, the axial force provided to expand thespacer embodiments may be provided in two separate steps to expand thespacer horizontally and then vertically. In another method of theinvention, the axial force may be provided continuously, resulting insmooth unbroken horizontal expansion followed immediately by verticalexpansion, with no break between the expansions. In other methods,vertical expansion may be provided before horizontal expansion.

In a method of the invention, the axial force provided to expand thespacer embodiments may be provided by engagement with a screw such aslockout screw 654. This method could be advantageous if the spacer is tobe implanted without addition of any bone graft material.

Following expansion of spacer 100, 400, 600, 900, 1000 or any embodimentdisclosed herein, bone graft and/or other materials may be depositedinto the respective inner chamber including 320, 520 or 820. Suitablematerials may include allograft, autograft, demineralized bone matrix,bone chips, bone growth stimulator, bone morphogenetic protein(s),beta-tricalcium phosphate, and combinations thereof, among others. Thelockout screw 654, or an insert or other locking or fastening device maybe inserted and engaged with the spacer 100, 400, 600, 900, or 1000 toprevent unintentional collapse or backing out, and to keep the spacer ina rigid, stable configuration. Pedicle screws and/or rods may beimplanted in addition to one or more of the spacers disclosed within tofurther stabilize the spine during bone ingrowth. The spacers 100, 400,600, 900, or 1000 and their embodiments may be formed of one or more ofthe following materials alone or in combination, among others: stainlesssteel, titanium, ceramic, carbon/PEEK, and bone.

Various approaches may be implemented to implant one or more of thespacers disclosed herein in a portion of a spine to provide desireddegrees of vertebral support and/or lordotic correction. In one example,a transforaminal approach may be employed, and a single, relativelysmall spacer implanted into the intervertebral space and expanded. Inanother example, a posterior approach may be employed, and two spacersimplanted in the intervertebral space and expanded. In another example,a lateral approach may be employed, and a single relatively large spacerimplanted, expanded horizontally and the anterior support memberexpanded vertically to provide asymmetrical support. In another example,an anterior approach may be employed and an asymmetric spacer implantedand expanded to provide support consistent with lordosis at that portionof the spine. In an alternative example, an anterior approach may beemployed and a symmetric spacer implanted and expanded asymmetrically toprovide support consistent with lordosis at that portion of the spine.

Referring to FIGS. 25A-E, an interbody spacer 900 includes built infeatures to provide a lordotic or kyphotic correction when implantedinto an intervertebral space between adjacent vertebrae. In bothcollapsed and expanded configurations, the spacer 900 may be bilaterallyasymmetrical with respect to a vertical plane extending along a spaceraxis 902, as seen in FIG. 25E, and may be bilaterally symmetrical withrespect to a horizontal plane extending along spacer axis 902, as seenin FIG. 25D. The spacer 900 may include both lateral and verticalsymmetric expansion capabilities. Spacer 900 has a first end 910 and asecond end 912. The spacer 900 includes first and second end bodies 950,952, which are connected to first and second support members 930, 940 bylink members 960, 962, 964, 966. End bodies 950, 952 may be identical toend bodies 650, 652. Link members 960, 962, 964, 966 may be identical tolink members 660, 662, 664, 666. Use of identical components may provideease of manufacturing, assembly, and/or use. First support member 930includes a first upper body 932 having an upper face 920 and a firstlower body 934 having a lower face 922. The upper and lower bodies 932,934 are wedge-shaped such that upper face 920 and lower face 922 aresloped between the spacer first end 910 and second end 912, relative toa horizontal plane extending along spacer axis 902. The sloped outersurfaces provide an integrated lordotic correction when theintervertebral spacer is implanted between first and second vertebralbodies of a portion of a spine. Second support member 940 includes asecond upper body 942 having an upper face 924 and a second lower body944 having a lower face 926. Second upper body 942 is vertically tallerthan first upper body 932; similarly, second lower body 944 isvertically taller than second lower body 944.

In the embodiment shown, support bodies 930, 940 decrease in totalheight between the spacer first end 910 and second end 912; and secondsupport body 940 is thicker or taller than first support body 930. Thuswhen implanted between adjacent vertebral bodies, second support member940 provides increased height support relative to first support member930. The internal features of support bodies 930, 940 may be identicalto those of support bodies 630, 640, including recessedportions/expansion slots for engagement with link members as previouslydescribed, ramps, and retention features. Interbody spacer 900 may beimplanted and expanded, both laterally and vertically, as described forspacer 600. When properly positioned between two vertebral bodies, forone example with the taller first end 910 placed anteriorly, spacer 900may provide a lordotic correction. The extent of correction provided byspacer 900 can vary. For example, spacer 900 as depicted provides an 8°angle of correction. Other embodiments may provide more or lesscorrection ranging from 0 to 30° . In other embodiments, the heightinequality between support bodies 930, 940 could be attained bydiffering depths of recesses in the support bodies, and/or differentlysized link members or upper and/or lower bodies.

In a method of use, interbody spacer 900 may be implanted and expandedin situ according to the method described for spacer 600. An insertionand/or expansion instrument may grasp spacer 900 in the collapsedconfiguration, and insert the spacer between adjacent vertebral bodiesin a portion of a spine. The insertion instrument, or a separateexpansion instrument, may be engaged with second end body 952 andprovide axial force along axis 902 to decrease the distance betweenfirst and second end bodies 950, 952. As the first and second end bodies950, 952 are drawn together, link members 960, 962, 964, 966 pivotrelative to support bodies 930, 940, and the lateral distance betweenfirst and second support bodies 930, 940 increases. As force continuesto be applied along axis 902, first and second end bodies 950, 952 aredrawn closer together, and the link member second ends are urged intothe expansion slots o within support bodies 930, 940, thus pushing upperbody 932 away from lower body 934, and pushing upper body 942 away fromlower body 944 to attain vertical expansion of the spacer. Duringvertical expansion, the two upper bodies 932, 942 may move an equalvertical distance from their respective lower bodies 934, 944. Spacer900 may be provisionally and/or permanently locked in the horizontallyand vertically expanded configuration by retention features and/or alocking screw as described for spacer 600.

Referring to FIGS. 26A-C and 27A-E, an interbody spacer 1000 includesfeatures to provide a lordotic or kyphotic correction when implantedinto an intervertebral space between adjacent vertebrae. The spacer 1000may be bilaterally asymmetrical with respect to a vertical planeextending along a spacer axis 1002, as seen in FIG. 27E, and may bebilaterally symmetrical with respect to a horizontal plane extendingalong spacer axis 1002, as seen in FIG. 27D. Spacer 1000 may includeboth asymmetric lateral expansion and asymmetric vertical expansioncapabilities.

The spacer 1000 has a first end 1010 and a second end 1012. The spacer1000 includes first and second end bodies 1050, 1052, which areconnected to first and second support members 1030, 1040 by link members1060, 1062, 1064, 1066. End bodies 1050, 1052 may be similar to endbodies 650, 652, and include similar features such as instrument boresand stop surfaces. However first end body 1050 is asymmetric withrespect to a vertical plane extending along a spacer axis 1002, and theangles of stop surfaces on opposite sides of axis 1002 may differ fromone another, to allow the asymmetrical lateral expansion as seen inFIGS. 26B, 26C, 27B, and 27C. Second end body 1052 is also asymmetricwith respect to a vertical plane extending along a spacer axis 1002, andthe angles of stop surfaces on opposite sides of axis 1002 may differfrom one another; for example a stop face 1014 is shaped differentlythan a stop face 1016, guiding and limiting the asymmetrical lateralexpansion of support member 1030.

The spacer 1000 further comprises first and second support members 1030,1040. During vertical expansion of spacer 1000, first support member1030 does not expand or increase in height. Second support member 1040may vertically increase in height. In an alternative embodiment, therelative position of the support members may be reversed such that firstsupport member 1030 increases in height and second support member 1040does not. First support member 1030 includes a first upper body 1032having an upper face 1020 and a first lower body 1034 having a lowerface 1022. Second support member 1040 may be identical to support member640, and may include similar or identical features including first andsecond receptacles, recessed portions, and retaining features. Secondsupport member 1040 includes a a second upper body 1042 having an upperface 1024 and a second lower body 1044 having a lower face 1026. Theupper and lower bodies 1042, 1044 are wedge-shaped such that upper face1020 and lower face 1022 are sloped between the spacer first end 1010and second end 1012, relative to a horizontal plane extending alongspacer axis 1002. The sloped outer faces provide an integrated lordoticcorrection when the intervertebral spacer is implanted between first andsecond vertebral bodies of a portion of a spine. Link members 1064, 1066may be identical to link members 664, 666.

Referring to FIG. 27C, upper bodies 1032 and 1042 are absent in order tobetter view the lower bodies and link members. Link members 1060, 1062are sized and shaped in order to permit the asymmetrical lateralexpansion of first support member 1030. As seen in FIG. 27C, link member1060 is relatively longer than link member 1062, allowing a first end1031 of first support member 1030 to project laterally farther away fromspacer axis 1002 than a second end 1033 of first support member 1030,when the spacer 1000 is laterally expanded. Upper and lower supportbodies 1032, 1034 may be mirror images of each other. Each support body1032, 1034 may include first and second receptacles 1008, 1010 forreceiving links 1060, 1062 and permitting rotation of links 1060, 1062within the receptacles during expansion of spacer 1000. Since supportmember 1030 does not expand vertically, expansion slots may be absentfrom the first and second support bodies 1032, 1034.

In an embodiment, second upper and lower bodies 1042, 1044 of verticallyexpandable support member 1040 may be identical to second upper andlower bodies 642, 644 of spacer 600 and/or second upper and lower bodies942, 944 of spacer 900. Links 1064, 1066 may be identical to links 664,666 of spacer 600 and/or links 964, 966 of spacer 900. Referring toFIGS. 27A-27C, it can be seen that in all configurations, the two endbodies 1050, 1052 are free from direct contact with one another, andfree from direct contact with support members 1030, 1040. The otherspacer embodiments disclosed herein may also be similarly configured.

In a method of use, spacer 1000 may be inserted and expanded accordingto one or more of the steps described for spacer 600 or 900. In itscollapsed configuration as seen in FIG. 26A, spacer 1000 may be engagedwith an insertion instrument and inserted between first and secondvertebral bodies. An instrument may provide axial force along axis 1002,drawing first end body 1050 toward second end body 1052 along axis 1002,and urging links 1060, 1062, 1064, and 1066 to rotate laterally outwardrelative to the end bodies, thus horizontally expanding the spacer. Thehorizontal expansion may be asymmetrical, as illustrated in FIGS. 26Band 17A, with at least one of the first and second support bodies movingto a non-parallel juxtaposition relative to spacer axis 1006. Furtherforce along axis 1006 may draw the first and second end bodies closertogether to urge vertical expansion of second support member 1040.During the vertical expansion step, links 1064, 1066 are prevented fromadditional lateral rotation and slide into expansion slots 1114, 1124 onsecond lower body 1044 and opposing expansion slots on second upper body1042, thus forcing second upper body 1042 vertically away from secondlower body 1044. In addition, as second support member 1040 expandsvertically relative to spacer axis 1002, first support member 1030 maycontinue to expand laterally relative to spacer axis 1002, as shown inFIGS. 26C and 27C. When the desired amount of vertical and lateralexpansion is achieved, spacer 1000 may be provisionally locked in thevertically and laterally expanded configuration by retention of links1064, 1066 in expansion slots 1114, 1124, and may also be secondarily orfinally locked by engagement of locking screw 654, or another lockingdevice.

Various features of the embodiments disclosed herein may be mixed andmatched to provide additional configurations which fall within the scopeof the invention. By way of non-limiting example, features and expansioncapabilities of the embodiments disclosed herein may be combined toprovide a symmetrical spacer embodiment providing no lordoticcorrection; a symmetrical spacer embodiment which provides a lordoticcorrection; an asymmetrical spacer embodiment providing no lordoticcorrection; and an asymmetrical spacer embodiment which provides alordotic correction. One or more embodiments may be implanted togetherto provide the precise support and/or correction needed to restoresagittal alignment and balance.

The phrases “connected to,” “coupled to” and “in communication with”refer to any form of interaction between two or more entities, includingmechanical, electrical, magnetic, electromagnetic, fluid, and thermalinteraction. Two components may be functionally coupled to each othereven though they are not in direct contact with each other. The term“abutting” refers to items that are in direct physical contact with eachother, although the items may not necessarily be attached together.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. While the various aspects of theembodiments are presented in drawings, the drawings are not necessarilydrawn to scale unless specifically indicated.

The terms “upper” and “lower”, “top” and “bottom”, “front” and “back”are used as relative terms herein for ease of description andunderstanding. It is understood that in embodiments of the disclosure,upper and lower, top and bottom, and/or front and back entities may bereversed.

Any methods disclosed herein comprise one or more steps or actions forperforming the described method. The method steps and/or actions may beinterchanged with one another. In other words, unless a specific orderof steps or actions is required for proper operation of the embodiment,the order and/or use of specific steps and/or actions may be modified.

Reference throughout this specification to “an embodiment” or “theembodiment” means that a particular feature, structure or characteristicdescribed in connection with that embodiment is included in at least oneembodiment. Thus, the quoted phrases, or variations thereof, as recitedthroughout this specification are not necessarily all referring to thesame embodiment.

Similarly, it should be appreciated that in the above description ofembodiments, various features are sometimes grouped together in a singleembodiment, Figure, or description thereof for the purpose ofstreamlining the disclosure. This method of disclosure, however, is notto be interpreted as reflecting an intention that any claim in this orany application claiming priority to this application require morefeatures than those expressly recited in that claim. Rather, as thefollowing claims reflect, inventive aspects lie in a combination offewer than all features of any single foregoing disclosed embodiment.Thus, the claims following this Detailed Description are herebyexpressly incorporated into this Detailed Description, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements recited inmeans-plus-function format are intended to be construed in accordancewith 35 U.S.C. §112 Para. 6. It will be apparent to those having skillin the art that changes may be made to the details of theabove-described embodiments without departing from the underlyingprinciples of the invention.

While specific embodiments and applications of the present inventionhave been illustrated and described, it is to be understood that theinvention is not limited to the precise configuration and componentsdisclosed herein. Various modifications, changes, and variations whichwill be apparent to those skilled in the art may be made in thearrangement, operation, and details of the methods and systems of thepresent invention disclosed herein without departing from the spirit andscope of the invention.

1. An intervertebral spacer for implantation between first and second vertebral bodies of a portion of a spine, the spacer having a first end and a second end and a first axis extending therebetween, the spacer comprising: a first support member comprising a first upper body and a first lower body; and a second support member; wherein the intervertebral spacer is expandable by an application of axial force along the first axis to expand the first support member away from the second support member along a first direction, and to expand the first upper body away from the first lower body along a second direction.
 2. The intervertebral spacer of claim 1, wherein the first direction is perpendicular to the first axis, and wherein the second direction is perpendicular to the first axis and to the first direction.
 3. The intervertebral spacer of claim 1, wherein the first direction is approximately parallel relative to the vertebral body endplates and the second direction is approximately perpendicular relative to the vertebral body endplates.
 4. The intervertebral spacer of claim 2, wherein the spacer is bilaterally symmetrical relative to at least one plane extending along the first axis.
 5. The intervertebral spacer of claim 2, the spacer further comprising: a first end body located at the spacer first end and connected to the first and second support members; and a second end body located at the spacer second end and connected to the first and second support members, wherein the axial force acts upon at least one of the end bodies to expand the spacer.
 6. The intervertebral spacer of claim 5, wherein the first end body is drawn toward to the second end body along the first axis to expand the spacer.
 7. The intervertebral spacer of claim 5, the spacer further comprising: a plurality of individual links, each link extending between and directly connecting one of the end bodies with one of the first and second support members.
 8. The intervertebral spacer of claim 7, wherein each of the individual links rotates laterally outward relative to the end body to which it is connected, to expand the first support member away from the second support member along the first direction.
 9. The intervertebral spacer of claim 8, wherein each of the individual links includes at least one stop surface, wherein the stop surface abuts one of the end bodies to limit expansion of the spacer along the first direction.
 10. The intervertebral spacer of claim 7, wherein each of the upper and lower bodies includes a first recess in communication with a second recess, wherein the first recess is recessed deeper within the body than the second recess.
 11. The intervertebral spacer of claim 10, wherein a ramp connects the first recess and the second recess, and wherein one of the individual links is urged from the first recess along the ramp into the second recess to expand the upper body away from the lower body along the second direction.
 12. The intervertebral spacer of claim 5, wherein the spacer further comprises: a collapsed configuration in which the first support member is immediately adjacent the second support member, and the first lower body abuts the first upper body; a laterally expanded configuration wherein the first support member is expanded away from the second support member along the first direction; a vertically expanded configuration wherein the first upper body is expanded away from the first lower body along the second direction; and a provisional locking structure which is integrally formed into each of the first and second support members, wherein the provisional locking structure prevents unintentional collapse of the spacer out of the vertically expanded configuration.
 13. The intervertebral spacer of claim 12, further comprising a supplementary locking structure, wherein the supplementary locking structure is engageable with at least one of the first and second end bodies to lock the spacer in the vertically expanded configuration.
 14. The intervertebral spacer of claim 12, wherein the second support member comprises a second upper body and a second lower body; wherein when the spacer is in the collapsed configuration the second lower body abuts the second upper body; and wherein when the spacer is in the vertically expanded configuration the second upper body is expanded away from the second lower body along the second direction.
 15. The intervertebral spacer of claim 1, wherein at least one of the first upper body or first lower body includes an outer surface which is sloped with respect to the first axis, the sloped outer surface providing an integrated lordotic correction when the intervertebral spacer is implanted between first and second vertebral bodies of a portion of a spine.
 16. A method for implanting an intervertebral spacer between first and second vertebral bodies of a portion of a spine, the spacer having a first end and a second end and a first axis extending therebetween, the method comprising: inserting a spacer between first and second vertebral bodies of a portion of a spine, the spacer comprising a first support member comprising a first upper body and a first lower body, and a second support member; and providing an application of axial force along the first axis, wherein the axial force moves the first support member away from the second support member along a first direction, and moves the first upper body away from the first lower body along a second direction.
 17. The method of claim 16, wherein the first direction is perpendicular to the first axis, and wherein the second direction is perpendicular to the first axis and to the first direction.
 18. The method of claim 17, wherein the axial force along the first axis expands the spacer laterally along the first direction and then sequentially expands the spacer vertically along the second direction only after lateral expansion is completed.
 19. The method of claim 17, wherein the spacer further comprises a first end body located at the spacer first end and connected to the first and second support members, and a second end body located at the spacer second end and connected to the first and second support members, the method further comprising: drawing the first end body toward to the second end body along the first axis to expand the spacer.
 20. The method of claim 19, wherein the spacer further comprises a plurality of individual links, each link directly connecting one of the end bodies with one of the first and second support members, the method further comprising: rotating each of the individual links laterally outward relative to the end body to which it is connected, to expand the first support member away from the second support member along the first direction. 